Ultrasonic material applicators and methods of use thereof

ABSTRACT

A method of controlling application of material onto a substrate includes ejecting atomized droplets from an array of micro-applicators while the array of micro-applicators cyclically moves about at least one axis. The atomized droplets from each of the plurality of micro-applicators overlap with atomized droplets from adjacent micro-applicators and a diffuse overlap of deposited atomized droplets from adjacent micro-applicators is provided on a surface of the substrate. The array of micro-applicators cyclically rotates back and forth around the at least one axis and/or moves back and forth parallel to the at least one axis. For example, the at least one axis can be a central axis of the array of micro-applicators, a length axis of the array of micro-applicators, a width axis of the array of micro-applicators, and the like. Also, the array of micro-applicators can be part of an ultrasonic material applicator used to paint vehicles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional application Ser. No.62/624,013, filed on Jan. 30, 2018. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present disclosure relates to the painting of vehicles, and moreparticularly to methods and equipment used in high volume production topaint the vehicles and components thereof.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Painting automotive vehicles in a high volume production environmentinvolves substantial capital cost, not only for application and controlof the paint, but also for equipment to capture overspray. The overspraycan be up to 40% of the paint that exits an applicator, or in otherwords, up to 40% of the paint that is purchased and applied is wasted(i.e. the transfer efficiency is ˜60%). Equipment that capturesoverspray involves significant capital expenses when a paint shop isconstructed, including large air handling systems to carry overspraydown through a paint booth, construction of a continuous stream of waterthat flows under a floor of the paint booth to capture the overspray,filtration systems, and abatement, among others. In addition, costs tooperate the equipment is high because air (flowing at greater than 200KCFM) that flows through the paint booths must be conditioned, the flowof water must be maintained, compressed air must be supplied, andcomplex electrostatics are employed to improve transfer efficiency.

With known production equipment, paint is atomized by rotating bells,which are essentially a rotating disk or bowl that spins at about20,000-80,000 rpms. The paint is typically ejected from an annular sloton a face of the rotating disk and is transported to the edges of thebell via centrifugal force. The paint then forms ligaments, which thenbreak into droplets at the edges of the bell. Although this equipmentworks for its intended purpose, various issues arise as a result of itsdesign. First, the momentum of the paint is mostly lateral, meaning itis moving off of the edge of the bell rather than towards the vehicle.To compensate for this movement, shaping air is applied that redirectsthe paint droplets towards the vehicle. In addition, electrostatics areused to steer the droplets towards the vehicle. The droplets have afairly wide size distribution, which can cause appearance issues.

Ultrasonic atomization is an efficient means of producing droplets witha narrow size distribution with a droplet momentum perpendicular to theapplicator surface (e.g., towards a surface of a vehicle). However,streams of droplets with a narrow size distribution may not provide acoating with uniform thickness.

This issue of coating uniformity, among other issues related to thepainting of automotive vehicles or other objects in a high volumeproduction environment, are addressed by the present disclosure.

SUMMARY

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

In one form of the present disclosure a method of controllingapplication of material onto a substrate includes ejecting atomizeddroplets from an array of micro-applicators while the array ofmicro-applicators cyclically moves about at least one axis such that theatomized droplets from each of the plurality of micro-applicatorsoverlap with atomized droplets from adjacent micro-applicators and adiffuse overlap of deposited atomized droplets from adjacentmicro-applicators is provided on a surface of the substrate. In someaspects of the present disclosure, the array of micro-applicatorscyclically rotate back and forth, e.g., at a predetermined frequency,around the at least one axis. In other aspects of the presentdisclosure, the array of micro-applicators moves back and forth parallelto the at least one axis. In some aspects of the present disclosure, theat least one axis is a central axis of the array of micro-applicators.In other aspects of the present disclosure, the at least one axis is alength axis of the array of micro-applicators, a width axis of the arrayof micro-applicators, a pair of orthogonal axes of the array ofmicro-applicators, and the like. In aspects where the at least one axisis a pair of orthogonal axes, the array of micro-applicators are enabledto move back and forth, parallel to each of the pair of orthogonal axes.

In some aspects of the present disclosure, the array ofmicro-applicators is part of an ultrasonic material applicator and/orthe surface of the substrate can be a surface of a vehicle. In suchaspects, a vehicle can be painted by ejecting the atomized droplets fromthe array of micro-applicators and moving the array of micro-applicatorscyclically about the at least one axis.

In another form of the present disclosure, a method for applying acoating to a vehicle includes ejecting atomized droplets of a coatingmaterial from an array of micro-applicators. The atomized dropletstravel line-of-sight from the array of micro-applicators to a surface ofthe vehicle and the array of applicators are moved along a patternadjacent to the surface of the vehicle such that the surface is coatingwith the coating material. The array of micro-applicators cyclicallymove about an axis of the array of micro-applicators such that theatomized droplets from each of the plurality of micro-applicatorsoverlap with atomized droplets from adjacent micro-applicators anddiffuse overlap with each other to form the coating on the surface ofthe vehicle without streaks.

In some aspects of the present disclosure, the array ofmicro-applicators rotates back and forth, e.g., at a predeterminedfrequency, around the axis of the array of micro-applicators. In otheraspects of the present disclosure, the array of micro-applicators movesback and forth, e.g., at a predetermined frequency, parallel to the axisof the array of micro-applicators.

In still another form of the present disclosure, an ultrasonicatomization material applicator includes at least one array ofmicro-applicators and at least one supply line configured to supply atleast one material to each of the micro-applicators. At least oneultrasonic transducer is mechanically coupled to the at least one arrayof micro-applicators. The at least one ultrasonic transducer isconfigured to vibrate the at least one array of micro-applicators suchthat atomized droplets of the at least one material are ejected fromeach of the micro-applicators. A movement device is mechanically coupledto the at least one array of micro-applicators. The movement device isconfigured to cyclically move the at least one array ofmicro-applicators back and forth about an axis of the at least one arrayof micro-applicators such that the atomized droplets from each of theplurality of micro-applicators overlap with atomized droplets fromadjacent micro-applicators due to the cyclic moving of the array ofmicro-applicators about the axis.

In some aspects of the present disclosure, the movement device is arotational movement device configured to cyclically rotate the at leastone array of micro-applicators back and forth around the axis at apredetermined frequency. In other aspects of the present disclosure, themovement device is a translational movement device configured tocyclically move the at least one array of micro-applicators back andforth along the axis at a predetermined frequency. Also, the ultrasonicatomization material applicator may include a robotic arm configured tomove the at least one array of micro-applicators across a surface alonga pattern while the movement device cyclically moves the at least onearray of micro-applicators back and forth about the axis of the at leastone array of micro-applicators.

DRAWINGS

In order that the disclosure may be well understood, there will now bedescribed various forms thereof, given by way of example, referencebeing made to the accompanying drawings, in which:

FIG. 1 is a planar view of an exemplary paint spray system according tothe teachings of the present disclosure;

FIG. 2A schematically depicts a planar view of an array ofmicro-applicators according to the teachings of the present disclosure;

FIG. 2B schematically depicts a side cross-sectional view of section2B-2B in FIG. 2A;

FIG. 3A schematically depicts a planar view of an array ofmicro-applicators that rotate back and forth about an applicator axisaccording to the teachings of the present disclosure;

FIG. 3B schematically depicts a side cross-sectional view of section3B-3B in FIG. 3A;

FIG. 3C schematically depicts another side cross-sectional view ofsection 3B-3B in FIG. 3A;

FIG. 4A schematically depicts a planar view of an array ofmicro-applicators that move back and forth along an axis according tothe teachings of the present disclosure;

FIG. 4B schematically depicts a planar view of an array ofmicro-applicators that move back and forth along an axis according tothe teachings of the present disclosure; and

FIG. 5 schematically depicts a flow chart for a method according to theteachings of the present disclosure.

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.Examples are provided to fully convey the scope of the disclosure tothose who are skilled in the art. Numerous specific details are setforth such as types of specific components, devices, and methods, toprovide a thorough understanding of variations of the presentdisclosure. It will be apparent to those skilled in the art thatspecific details need not be employed and that the examples providedherein, may include alternative embodiments and are not intended tolimit the scope of the disclosure. In some examples, well-knownprocesses, well-known device structures, and well-known technologies arenot described in detail.

The present disclosure provides a variety of devices, methods, andsystems for controlling the application of paint to automotive vehiclesin a high production environment, which reduce overspray and increasetransfer efficiency of the paint. It should be understood that thereference to automotive vehicles is merely exemplary and that otherobjects that are painted, such as industrial equipment and appliances,among others, may also be painted in accordance with the teachings ofthe present disclosure. Further, the use of “paint” or “painting” shouldnot be construed as limiting the present disclosure, and thus othermaterials such as coatings, primers, sealants, cleaning solvents, amongothers, are to be understood as falling within the scope of the presentdisclosure.

Generally, the teachings of the present disclosure are based on adroplet spray generation device in which a perforate membrane is drivenby a piezoelectric transducer. This device and variations thereof aredescribed in U.S. Pat. Nos. 6,394,363, 7,550,897, 7,977,849, 8,317,299,8,191,982, 9,156,049, 7,976,135, 9,452,442, and U.S. PublishedApplication Nos. 2014/0110500, 2016/0228902, and 2016/0158789, which areincorporated herein by reference in their entirety.

Referring now to FIG. 1, a paint spray system 2 for painting a part Pusing a robotic arm 4 is schematically depicted. The robotic arm 4 iscoupled to at least one material applicator 10 and a rack 5. A materialsource 8 (e.g., a paint source) is included and includes at least onematerial M (materials M₁, M₂, M₃, . . . Mn shown in FIG. 1; referred toherein simply as “material M” and “material(s)”). In some aspects of thepresent disclosure the material M includes paint materials, adhesivematerials, sealant materials, and the like. The arm 4 moves according toxyz coordinates with respect to rack 5 such that the material applicator10 moves across a surface (not labeled) of the part P. Also, a powersource 6 is configured to supply power to arm 4 and rack 5. The arm 4,rack 5, and power source 6 are configured to supply material M from thematerial source 8 to the material applicator 10 such that a coating isproduced on the surface of the part P. While FIG. 1 schematicallydepicts a paint system 2 with one robotic arm 4, it should be understoodthat paint spray systems 2 with more than one robotic arm 2 are includedin the teachings of the present disclosure.

Referring now to FIGS. 2A and 2B, a material applicator 10 according tothe teachings of the present disclosure is schematically shown. In oneform of the present disclosure, the material applicator 10 includes anarray plate 100 with an applicator axis 1 and an array ofmicro-applicators 102 comprising a plurality of micro-applicators 110.In some aspects of the present disclosure, the array plate 100 with thearray of micro-applicators 102 is positioned within a housing 140. Eachof the micro-applicators 110 comprises a plurality of apertures 112through which a material M is ejected such that atomized droplets 3 ofthe material is provided (FIG. 2B). Particularly, each of themicro-applicators 110 includes a micro-applicator plate 114 with theplurality of apertures 112 extending through the micro-applicator plate114. In one aspect of the present disclosure, each of themicro-applicators 110 includes a transducer 120. In another aspect ofthe present disclosure, only a subset of the micro-applicators 110include a transducer. However, in both aspects of the present disclosureeach of the micro-applicator plates 114 are in mechanical communicationwith a transducer 120 such that excitation (i.e., vibration) of at leastone transducer 120 vibrates each of micro-applicator plates 114 asschematically depicted by the horizontal (z-direction) double-headedarrows in FIG. 2B.

The micro-applicator 110, i.e., each of the micro-applicators 110includes a frame 130 and a material inlet 136. The frame 130 includes aback wall 131 and at least one sidewall 132 such that a reservoir 134for containing the material M is provided between the back wall 131 andthe micro-applicator plate 114. The inlet 136 is in fluid communicationwith the reservoir 134 such that the Material M flows through the inlet136 and into the reservoir 134. In some aspects of the presentdisclosure, the transducer 120 is positioned between themicro-applicator plate 114 and the frame 130. For example, thetransducer 120 may be positioned between an outer edge surface 115 ofthe micro-applicator plate 114 and an inner surface 133 of a sidewall132.

Still referring to FIG. 2B, surface tension of the material M resiststhe material M from flowing through the apertures 112 of themicro-applicator plate 114 unless the transducer 120 is activated andvibrates. That is, when the transducer 120 is activated and vibrates,the material M is ejected through and/or from the plurality of apertures112 to provide a stream 5 of atomized droplets 3. The stream 5 ofatomized droplets 3 propagates generally line-of-sight from theapertures 112 (and the array of micro-applicator 110) to the substrate Sand forms a coating C on a surface s′ of a substrate S. That is, thestream 5 of atomized droplets 3 propagates generally parallel to amicro-applicator axis 1′ and forms the coating C on a surface s′ of asubstrate S. As schematically depicted in FIG. 2B, the atomized droplets3 have a narrow droplet size distribution (e.g., average dropletdiameter) and may result in a thickness (z-direction) of the coating Cnot being uniform and having streaks. For example, if the materialapplicator 10 moves across the surface s′ along the x-direction depictedin the figures, the alternating thin-thick thicknesses along they-direction of the coating C will appear as streaks along thex-direction. As used herein, the term “streak” or “streaks” refers tocoating with a non-uniform thickness such that the coating has anon-uniform appearance when viewed by an observer.

Referring now to FIGS. 3A and 3B, a material applicator 12 for providinga coating with a uniform thickness (i.e., without streaks) according tothe teachings of the present disclosure is schematically shown. In oneform of the present disclosure, the material applicator 12 includes thesame array plate 100, applicator axis 1, transducers 120, frame 130, andhousing 140 as the material applicator 10 (FIGS. 2A-2B). However, insome aspects of the present disclosure the array plate 100 rotates backand forth about the applicator axis 1. In such aspects, a movementdevice 150 (e.g. a motor), may be in mechanical and/or electricalcommunication with the array plate 100 and be configured to rotate thearray plate 100 back and forth within the housing 140. For example, themovement device 150 in combination with bearings 160, a journal surface(not labeled), and the like, may provide rotation of the array plate 100back and forth within the housing 140. In the alternative, or inaddition to, the movement device 150 may provide rotation of the arrayplate 100 and the housing 140 back and forth around the applicator axis1. As used herein, the phrase “back and forth” refers to rotating ormoving in a first direction about an axis followed by rotating or movingin a second direction about the axis that is generally opposite to thefirst direction as schematically depicted by the double-headed arrows inFIG. 3A.

It should be understood that the array plate 100 may rotate a firstangle around the applicator axis 1 in the first direction and rotate asecond angle about the applicator axis 1 in the second direction. Insome aspects of the present disclosure, the first angle is the same asthe second angle. In other aspects of the present disclosure, the firstangle is not the same as the second angle. In some aspects of thepresent disclosure, the first angle and the second angle may be between1 and 45 degrees, for example between 5 and 30 degrees or between 10 and20 degrees. Also, the applicator axis 1 may be positioned at the centerof the array of micro-applicators 102 as schematically depicted in FIG.3A, or in the alternative, the applicator axis may be positioned offsetfrom the center of the array of micro-applicators 102 (not shown).

Referring particularly to FIG. 3B, rotation of the array plate 100 backand forth around the applicator axis 1 rotates each of themicro-apertures 110 around the applicator axis 1. Accordingly, and asthe array plate 100 rotates around the applicator axis 1, diffusestreams 5′ of atomized droplets 3 are ejected from the plurality ofapertures 112. The diffuse streams 5′ of atomized droplets 3 propagategenerally line-of-sight from the apertures 112 to the substrate S. Thatis, the diffuse streams 5′ of atomized droplets 3 propagate generallyparallel to a micro-applicator axis 1′. Also, the atomized droplets 3from each of the apertures 112 overlap with atomized droplets 3 fromadjacent apertures 112 such that the coating C′ has a uniform thickness(z-direction) and a uniform appearance (i.e., no streaks) across thesurface s′ (x- and y-directions) of the substrate S. It should beunderstood that in the alternative, or in addition to, atomized droplets3 from each of the micro-applicators 110 may overlap with atomizeddroplets 3 from adjacent micro-applicators 110 such that the coating C′on the surface s′ of the substrate S is provided without streaks. Thematerial applicator 12, and other material applicators described herein,may be used to provide a coating on a surface such as a paint coating,an adhesive coating, a sealant coating, and the like.

While FIG. 3B schematically depicts material M entering the reservoir134 through the inlet 136 and exiting the reservoir 134 through theapertures 112, it should be understood that other flow configurations ofthe material M are included in the teachings of the present disclosure.For example, FIG. 3C schematically depicts a micro-applicator 110 withthe frame 132 comprising an inlet 138 and an outlet 139 such thatmaterial M enters the reservoir 134 through the inlet 138 and exits thereservoir 134 through the plurality of apertures 112 and the outlet 139.It should be understood that the outlet 139 provides additionalflexibility in the use of the material applicator 12. For example, therate of flow of the material M through the inlet 138 can be used toadjust the pressure of the material M in the reservoir 134 and therebycan be used to adjust a flow rate and/or atomized droplet size of theatomized droplets 3.

Referring now to FIGS. 4A and 4B, in another form of the presentdisclosure a material applicator 20 with a non-circular shape isprovided. Particularly, the material applicator 20 has a rectangularshaped array plate 200 with an applicator array 202 comprising aplurality of the micro-applicators 110. Each of the micro-applicators110 includes the plurality of apertures 112 as discussed above withreference to FIGS. 3A-3B. The array plate 200 with the plurality ofmicro-applicators 100 moves along a length (x-direction) axis 201Land/or a width (y-direction) axis 201W of the material applicator 20.For example, one or more movement devices 260 (FIG. 4A); also referredto herein as “mechanical actuators 260”) and/or one or more movementdevices 270 (FIG. 4B; also referred to herein as “cams 270”) may bepositioned between the array plate 200 and a housing 240. The one ormore mechanical actuators 260 are configured to expand and contract suchthat the array plate 200 moves back and forth generally parallel to thelength axis 201L; back and forth generally parallel to the width axis201W; back and forth generally at an angle not equal to zero along thelength axis 201L and the width axis W; and back and forth generallytranslating in a curved motion between the length axis 201L and thewidth axis 201W. Also, the one or more cams 270, with an optionalbiasing member 274 (e.g., a spring), are configured to rotate about acam axis 272 such that the array plate 200 moves back and forthgenerally parallel to the length axis 201L; back and forth generallyparallel to the width axis 201W; back and forth generally at an anglenot equal to zero along the length axis 201L and the width axis W; andback and forth generally translating in a curved motion between thelength axis 201L and the width axis 201W. It should be understood thatthe one or more mechanical actuators 260 and/or one or more cams 270 maybe configured to move array plate 200 back and forth at an angle notequal to zero along the length axis 201L and/or width axis 201W.Furthermore, the movements, rotationally or translationally, can betuned to an algorithm, frequency, program, and/or waveform with aperiodicity (e.g., frequency) ranging from the infrasonic range (i.e.,less than 15 Hz) up to and including the ultrasonic range (i.e.,20,000-100,000 Hz).

It should be understood that the array plate 200 may move a firstdistance along the length of the length axis 201L and/or width axis 201Win a first direction and move a second distance along the length of thelength axis 201L and/or width axis 201W in a second direction that isgenerally opposite the first direction. In some aspects of the presentdisclosure, the first distance is the same as the second distance. Inother aspects of the present disclosure, the first distance is not thesame as the second distance. In some aspects of the present disclosure,the first distance and the second distance may be between 1 mm and 10mm, for example between 1 mm and 5 mm or between 2 mm and 5 mm. Also,the applicator axis 1 may be positioned at the center of the array ofmicro-applicators 102 as schematically depicted in FIG. 3A, or in thealternative, the applicator axis may be positioned offset from thecenter of the array of micro-applicators 102 (not shown).

The plurality of micro-applicators 110 of the material applicator 20eject atomized droplets 3 that propagate in a direction generallyparallel to a micro-applicator axis 1′ (FIG. 2B) as described above forthe material applicator 10. Also, and in addition to the material beingejected through the plurality of apertures 112, movement of the arrayplate 200 back and forth along the length axis 201L and/or width axis201W moves each of the micro-apertures 110 such that a diffuse stream 5′of atomized droplets 3 is provided by the plurality of apertures 112 anda coating C′ on the surface s′ of a substrate S without streaks isprovided (FIG. 3B). In the alternative, or in addition to, atomizeddroplets 3 from each of the micro-applicators 110 in the materialapplicator 20 may overlap with atomized droplets 3 from adjacentmicro-applicators 110 such that the coating C′ on the surface s′ of thesubstrate S is provided without streaks.

It should be understood that material applicators with a plurality ofmicro-applicators having different shapes than circular or rectangular(e.g., triangular, elliptical, etc.) as schematically depicted in FIGS.2A-4B are included within the teachings of the present disclosure.

Referring now to FIGS. 3A-3B and 5, a flow chart for a method 30 ofcontrolling application of material onto a substrate according to theteachings of the present disclosure is shown in FIG. 5. The method 30includes flowing a material M into a material applicator 12 thatcomprises a plurality of micro-applicators 110 at step 300. Each of theplurality of micro-applicators 110 includes a plurality of apertures 112and a reservoir 134 such that the material M flows into the reservoir134. The material M is ejected through and/or from each of the pluralityof apertures 112 in the form of atomized droplets 3, travel in adirection that is generally parallel to a micro-applicator axis 1′ ofthe micro-applicator 110 and are deposited on a surface s′ of asubstrate S at step 310. During the ejection of the material M from theplurality of apertures 112, the material applicator 12 is rotated backand forth about the applicator axis 1 at step 320. Rotation of thematerial applicator 12 back and forth about the applicator axis 1results in a diffuse stream 5′ of atomized droplets 3 from each of theplurality of apertures 112. That is, atomized droplets 3 from each ofthe plurality of apertures 112 overlap with atomized droplets 3 fromadjacent apertures 112 such that a coating C′ with a generally uniformthickness (z-direction) and without streaks is formed on the surface s′.

While FIG. 5 schematically depicts a method 30 of controllingapplication of material onto a substrate with reference to FIGS. 3A-3B,it should be understood that the method 30 may include the materialapplicator 20 schematically depicted in FIGS. 4A-4B.

The material applicator 12, and other material applicators disclosedherein, may be formed from known materials used in the manufacture ofmaterial applicators. The array plate 100, the micro-applicator plate114, the frame 130 and the housing 140 may be formed from metallicmaterials, polymer materials, ceramic materials, and/or compositesmaterials. Non-limiting examples of metallic materials include steels,stainless steels, nickel-base alloys, cobalt-base alloys, and the like.Non-limiting examples of polymer materials include nylon, low-densitypolyethylene (LDPE), high-density polyethylene (HDPE), polypropylene(PP), polyvinyl chloride (PVC), and the like. Non-limiting examples ofceramic materials include alumina (Al2O3), silica (SiO2), mullite (e.g.,3Al₂O₃.2SiO₂), titanium nitride (TiN), and the like. Non-limitingexamples of composite materials include fiber reinforced polymers,ceramic matrix composites, metal matrix composites, and the like. Thetransducer 120 may be formed from piezoelectric materials such as bariumtitanate (BaTiO₃), lead zirconate titanate (PZT), potassium niobite(KNbO₃), sodium tungstate (Na₂WO₄) and the like. The material M may beat least one material used to form a coating or layer on a surface of asubstrate.

It should be understood from the teachings of the present disclosurethat a material applicator and a method of using a material applicatorproviding a coating with a uniform thickness are provided. The materialapplicator includes an array of micro-applicators and eachmicro-applicator has a plurality of apertures through which a materialis ejected. At least one transducer is mechanically coupled to the arrayof micro-applicators such that a stream of atomized droplets propagatesgenerally parallel to an array axis. Also, the array ofmicro-applicators rotate back and forth around the array axis and/ormove back and forth along a length and/or width axis of the array ofmicro-applicators such that a diffuse stream of the atomized droplets isprovided. Propagation of the diffuse stream of atomized dropletsgenerally parallel to the array axis reduces overspray during theapplication of a paint, adhesive and/or sealant onto the surface of thesubstrate.

Unless otherwise expressly indicated herein, all numerical values anddirectional terms indicating dimensions and/or tolerances, or othercharacteristics are to be understood as modified by the word “about” or“generally” in describing the scope of the present disclosure. Thismodification is desired for various reasons including industrialpractice, manufacturing technology, and testing capability.

It should be noted that the disclosure is not limited to the embodimentdescribed and illustrated as examples. A large variety of modificationshave been described and more are part of the knowledge of the personskilled in the art. These and further modifications as well as anyreplacement by technical equivalents may be added to the description andfigures, without leaving the scope of the protection of the disclosureand of the present patent.

What is claimed is:
 1. A method of controlling application of materialonto a substrate comprising: ejecting atomized droplets from an array ofmicro-applicators, wherein the atomized droplets travel line-of-sightfrom the array of micro-applicators to a surface of the substrate; andmoving the array of micro-applicators cyclically about at least one axissuch that the atomized droplets from each of the plurality ofmicro-applicators overlap with atomized droplets from adjacentmicro-applicators and diffuse overlap of deposited atomized dropletsfrom adjacent micro-applicators is provided on the surface.
 2. Themethod according to claim 1, wherein the array of micro-applicatorscyclically rotates back and forth around the at least one axis of thearray of micro-applicators.
 3. The method according to claim 2, whereinthe array of micro-applicators rotates back and forth around the atleast one axis of the array of micro-applicators at a predeterminedfrequency.
 4. The method according to claim 1, wherein the array ofmicro-applicators moves back and forth parallel to the at least one axisof the array of micro-applicators.
 5. The method according to claim 4,wherein the array of micro-applicators moves back and forth parallel tothe at least one axis of the array of micro-applicators at apredetermined frequency.
 6. The method according to claim 1, wherein theat least one axis is a pair of orthogonal axes and the array ofmicro-applicators moves back and forth parallel to each of the pair oforthogonal axes.
 7. The method according to claim 1, wherein the axis ofthe array of micro-applicators is a central axis of the array ofmicro-applicators.
 8. The method according to claim 1, wherein the arrayof micro-applicators is part of an ultrasonic material applicator. 9.The method according to claim 1, wherein the surface of the substrate isa surface of a vehicle.
 10. The method of according to claim 1 furthercomprising painting a vehicle by ejecting the atomized droplets from thearray of micro-applicators and moving the array of micro-applicatorscyclically about the at least one axis.
 11. A method for applying acoating to a vehicle comprising: ejecting atomized droplets of a coatingmaterial from an array of micro-applicators, wherein the atomizeddroplets travel line-of-sight from the array of micro-applicators to asurface of the vehicle; moving the array of applicators along a patternadjacent to the surface of the vehicle such that the surface is coatingwith the coating material; and moving the array of micro-applicatorscyclically about an axis of the array of micro-applicators such that theatomized droplets from each of the plurality of micro-applicatorsoverlap with atomized droplets from adjacent micro-applicators due tothe moving of the array of micro-applicators about the axis and providea diffuse overlap with each other to form the coating on the surface ofthe vehicle without streaks.
 12. The method according to claim 11,wherein the array of micro-applicators rotates back and forth around theaxis of the array of micro-applicators.
 13. The method according toclaim 12, wherein the array of micro-applicators rotates back and fortharound the axis of the array of micro-applicators at a predeterminedfrequency.
 14. The method according to claim 11, wherein the array ofmicro-applicators moves back and forth along the axis of the array ofmicro-applicators.
 15. The method according to claim 14, wherein thearray of micro-applicators moves back and forth along the axis of thearray of micro-applicators at a predetermined frequency.
 16. The methodaccording to claim 11, wherein the axis of the array ofmicro-applicators is a central axis of the array of micro-applicators.17. An ultrasonic atomization material applicator comprising: at leastone array of micro-applicators; at least one supply line incommunication with the micro-applicators and configured to supply atleast one material to each of the micro-applicators; at least oneultrasonic transducer mechanically coupled to the at least one array ofmicro-applicators, wherein the at least one ultrasonic transducer isconfigured to vibrate the at least one array of micro-applicators suchthat atomized droplets of the at least one material are ejected fromeach of the micro-applicators; and a movement device mechanicallycoupled to the at least one array of micro-applicators, wherein themovement drive is configured to cyclically move the at least one arrayof micro-applicators back and forth about an axis of the at least onearray of micro-applicators such that the atomized droplets from each ofthe plurality of micro-applicators overlap with atomized droplets fromadjacent micro-applicators due to the cyclic moving of the array ofmicro-applicators about the axis.
 18. The ultrasonic atomizationmaterial applicator of claim 17, wherein the movement device is arotational movement device configured to cyclically rotate the at leastone array of micro-applicators back and forth around the axis at apredetermined frequency.
 19. The ultrasonic atomization materialapplicator of claim 17, wherein the movement device is a translationalmovement device configured to cyclically move the at least one array ofmicro-applicators back and forth along the axis at a predeterminedfrequency.
 20. The ultrasonic atomization material applicator of claim17, further comprising a robotic arm configured to move the at least onearray of micro-applicators across a surface along a pattern while themovement device cyclically moves the at least one array ofmicro-applicators back and forth about the axis of the at least onearray of micro-applicators.